1. Technical Field
The invention relates to a device for monitoring the position of an oil/water contact (OWC) between an oil-continuous fluid overlying a water-continuous fluid inside a casing pipe, using a transmitter for a generating an electro-magnetic signal, and detecting a reflected signal from the oil-water contact.
2. Description of the Related Art
A device for using guided electromagnetic waves along the outside of a conductive casing is presented in U.S. Pat. No. 6,480,000 to Fan-Nian Kong et al.
U.S. Pat. No. 5,926,024 to Blount, “System and method for measuring fluid properties by forming a coaxial transmission line in a cased well”, is a logging instrument which transmits microwave frequency within a section of the wellbore. That apparatus is able to determine which zone is producing excessive amounts of water into the production fluids, but is incapable of measuring the distance down to an oil-water contact from a fixed position.
In order to produce a large proportion of oil from a well in which there is a risk of also producing water, there is an advantage in being able to monitor the depth to the oil-water contact (OWC) inside the production zone, inside the casing or screen through the production zone.